Generally, this type of apparatus is known as an apparatus for storing sheets fed from an apparatus such as an image formation apparatus on the upstream side on a stack tray. In this case, a jog sort mechanism is also known in which sheets are offset and collected on the tray so as to sort the sheets for each copy.
For example, Patent Document 1 discloses a storage mechanism for dropping a sheet fed from a sheet discharge outlet onto a tray where the stack tray is disposed with a level difference formed on the downstream side of a transport path for transporting the sheet, and an aligning mechanism for aligning the stored sheet in a predetermined position with a pair of right and left aligning plates.
In the aligning mechanism in the Document, a pair of right and left aligning plates are moved up and down from a waiting position above the tray to an actuation position below, guide a sheet carried out to above the tray from the sheet discharge outlet in a waiting position (posture), and after moving to the tray, align the sheet in the predetermined position in a width direction in the actuation position (posture).
Patent Document 2 discloses a jogger mechanism for sorting sheets carried onto the tray from the sheet discharge outlet for each copy. A pair of right and left aligning members (plates) are disposed to be able to shift to positions in the sheet width direction, and a mechanism is disclosed which moves the aligning members up and down between the waiting position above the tray and the actuation position on the tray. Then, sheets fed from the sheet discharge outlet are collected and sorted in different positions for each copy.